Compression ratio

yellow rose said
The higher the CR, the tighter the tuneup window. E85 is a bit more forgiving, but I wouldn’t use any more CR than you think you can tune.

This is all new to me

yellow rose said
The higher the CR, the tighter the tuneup window. E85 is a bit more forgiving, but I wouldn’t use any more CR than you think you can tune.

This is all new to me as I've never had a high compression engine so I'm interested in what the difference is in tuning higher compression